LiDAR APPARATUS USING INTERRUPTED CONTINUOUS WAVE LIGHT

ABSTRACT

A light detection and ranging (LiDAR) apparatus capable of extracting speed information and distance information of objects in front thereof is provided. The LiDAR apparatus includes: a continuous wave light source configured to generate continuous wave light; a beam steering device configured to emit the continuous wave light to an object for a first time and stop emitting the continuous wave light to the object for a second time; a receiver configured to receive the continuous wave light that is reflected from the object to form a reception signal; and a signal processor configured to obtain distance information and speed information about the object based on the reception signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2019-0164143, filed on Dec. 10, 2019, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND 1. Field

Apparatuses and methods consistent with example embodiments relate tolight detection and ranging (LiDAR) apparatuses, and more particularly,to LiDAR apparatuses capable of extracting speed information anddistance information of objects in front thereof by using interruptedcontinuous wave light.

2. Description of Related Art

Recently, an advanced driving assistance system (ADAS) with variousfunctions has been commercialized. For example, there is an increasingnumber of vehicles equipped with functions such as adaptive cruisecontrol (ACC) or autonomous emergency braking system (AEB). The ACC is afunction of recognizing the position and speed of another vehicle toreduce the speed when there is a risk of collision and to drive avehicle within a set speed range when there is no risk of collision. TheAEB is a system that prevents a collision by automatically braking whenthere is a risk of collision by recognizing a vehicle ahead, but thedriver does not respond to it or a response method is inappropriate. Inaddition, it is expected that automobiles capable of autonomous drivingwill be commercialized in the near future.

Accordingly, the importance of vehicle radar for providing frontinformation of a vehicle is gradually increasing. For example, LiDARsensors are commonly used as vehicle radars to measure the distance,velocity, azimuth position, etc. of a measurement target from a timewhen a scattered or reflected laser is returned after firing a laser, alaser intensity change, a laser frequency change, a polarization statechange of the laser, or the like.

LiDAR sensors are classified into time of flight (ToF)-type sensorsusing pulses and frequency modulated continuous wave (FMCW)-type sensorsusing continuous wave light. In the case of the ToF type-sensors usingpulses, a wideband receiver may be needed because the pulses include awide frequency band. This makes noise suppression difficult. On theother hand, in the case of the FMCW type-sensors using continuous wavelight, although noise may be suppressed using a narrowband receiver, theFMCW type-sensors may use a high power continuous wave light source,which is difficult to implement and expensive.

SUMMARY

Example embodiments address at least the above problems and/ordisadvantages and other disadvantages not described above. Also, theexample embodiments are not required to overcome the disadvantagesdescribed above, and may not overcome any of the problems describedabove.

One or more example embodiments provide light detection and ranging(LiDAR) apparatuses capable of extracting the speed information anddistance information of objects in front thereof by using interruptedcontinuous wave light.

Further, one or more example embodiments provide LiDAR apparatusescapable of suppressing noise by using a narrowband receiver and capableof using a low cost low power continuous wave light source.

According to an aspect of an example embodiment, there is provided alight detection and ranging (LiDAR) apparatus including: a continuouswave light source configured to generate continuous wave light; a beamsteering device configured to emit the continuous wave light to anobject for a first time and stop emitting the continuous wave light tothe object for a second time; a receiver configured to receive thecontinuous wave light that is reflected from the object to form areception signal; and a signal processor configured to obtain distanceinformation and speed information about the object based on thereception signal.

The beam steering device may be further configured to periodicallyrepeat an operation of emitting the continuous wave light for the firsttime and an operation of stopping emitting the continuous wave light forthe second time.

The second time may be greater than the first time.

The first time may be in a range of 1 ns to 1,000 ns.

The LiDAR apparatus may include: a beam splitter configured to provide afirst portion of the continuous wave light generated by the continuouswave light source to the beam steering device so that the first portionof the continuous wave light is emitted to and reflected from theobject, and then received by the receiver, and provide a second portionof the continuous wave light to the receiver, wherein the receiver maybe further configured to form the reception signal by combining thefirst portion of the continuous wave light received by the receiver, andthe second portion of the continuous wave light provided from the beamsplitter, and causing the first portion and the second portion of thecontinuous wave light to interfere with each other.

The LiDAR apparatus may further include: an optical amplifier configuredto amplify the continuous wave light generated by the continuous wavelight source and provide the amplified continuous wave light to the beamsteering device for the first time, and stop amplifying and outputtingthe continuous wave light for the second time.

The beam steering device may be further configured to emit thecontinuous wave light multiple times toward a first area in front of thebeam steering device and then emit the continuous wave light multipletimes toward a second area different from the first area.

The signal processor may be further configured to: accumulate aplurality of first reception signals received from the first area andobtain distance information and speed information about a first objectin the first area based on the accumulated plurality of first receptionsignals; and accumulate a plurality of second reception signals receivedfrom the second area and obtain distance information and speedinformation about a second object in the second area based on theaccumulated plurality of second reception signals.

The LiDAR apparatus may further include: a frequency modulatorconfigured to drive the continuous wave light source such that thecontinuous wave light source generates frequency-modulated continuouswave light, wherein the beam steering device may be further configuredto emit the frequency-modulated continuous wave light to the object forthe first time and stop emitting the frequency-modulated continuous wavelight to the object for the second time.

The signal processor may be further configured to obtain the distanceinformation and the speed information about the object by analyzing afrequency of the reception signal in a frequency-modulated continuouswave (FMCW) manner.

The frequency modulator may be configured to linearly increase afrequency of the frequency-modulated continuous wave light for a thirdtime.

The third time may be equal to a sum of the first time and the secondtime, and the beam steering device is further configured to emit thefrequency-modulated continuous wave light once for the third time.

The third time may be greater than a sum of the first time and thesecond time, and the beam steering device is further configured to emitthe frequency-modulated continuous wave light multiple times for thethird time.

The frequency modulator may be further configured to linearly increase afrequency of the frequency-modulated continuous wave light for a thirdtime and linearly decrease the frequency for a fourth time, wherein thethird time for increasing the frequency of the frequency-modulatedcontinuous wave light and the fourth time for decreasing the frequencyof the frequency-modulated continuous wave light may be periodicallyrepeated.

Each of the third time and the fourth time may be equal to a sum of thefirst time and the second time, and the beam steering device may befurther configured to emit the frequency-modulated continuous wave lightonce for the third time and emit the frequency-modulated continuous wavelight once for the fourth time.

Each of the third time and the fourth time may be greater than a sum ofthe first time and the second time, and the beam steering device may beconfigured to emit the frequency-modulated continuous wave lightmultiple times for the third time and emit the frequency-modulatedcontinuous wave light multiple times for the fourth time.

The signal processor may be further configured to obtain the distanceinformation and the speed information about the object in an FMCW mannerbased on the reception signal obtained from reflected light of thefrequency-modulated continuous wave light emitted for the third time andthe reception signal obtained from reflected light of thefrequency-modulated continuous wave light emitted for the fourth time.

The signal processor may be further configured to obtain the distanceinformation about the object by analyzing a waveform of the receptionsignal in a time of flight (ToF) manner.

The signal processor may be further configured to adjust the distanceinformation about the object based on the distance information extractedin the ToF manner and the distance information extracted in the FMCWmanner.

The signal processor may be further configured to extract the distanceinformation about the object by analyzing a waveform of the receptionsignal in a TOF manner and obtain the speed information about the objectby analyzing a frequency of the reception signal in a Doppler manner.

According to an aspect of an example embodiment, there is provided amethod of sensing an object by a light detection and ranging (LiDAR)apparatus, the method including: generating continuous wave light;splitting the continuous wave light into a first portion and a secondportion; amplifying the first portion of the continuous wave light;intermittently emitting the amplified first portion of the continuouswave light toward an object, the amplified first portion of thecontinuous wave light being reflected from the object and received by areceiver of the LiDAR apparatus; providing the second portion of thecontinuous wave light to the receiver; generating a reception signal bycombining the first portion of the continuous wave light and the secondportion of the continuous wave light that are received by the receiver;and obtaining distance information and speed information about theobject based on the reception signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will be more apparent by describingcertain example embodiments, with reference to the accompanyingdrawings, in which:

FIG. 1 is a block diagram illustrating a schematic configuration of alight detection and ranging (LiDAR) apparatus according to an exampleembodiment;

FIGS. 2A to 2C illustrate examples of a configuration and operation ofan optical phase array for scanning laser light;

FIG. 3 is a timing diagram showing an operation of the LiDAR apparatusshown in FIG. 1, according to an example embodiment;

FIG. 4 is a graph showing a frequency component of transmission lightand a frequency component of reception light in a linearfrequency-modulated continuous wave (FMCW) method;

FIG. 5 is a timing diagram showing an operation of the LiDAR apparatusshown in FIG. 1, according to another example embodiment;

FIG. 6 is a timing diagram showing an operation of the LiDAR apparatusshown in FIG. 1, according to another example embodiment;

FIG. 7 is a graph showing a frequency component of transmission lightand a frequency component of reception light in a triangular FMCWmethod;

FIG. 8 is a timing diagram showing an operation of the LiDAR apparatusshown in FIG. 1, according to another example embodiment;

FIG. 9 is a block diagram illustrating a schematic configuration of anLiDAR apparatus according to another example embodiment; and

FIG. 10 is a timing diagram showing an operation of the LiDAR apparatusshown in FIG. 9, according to an example embodiment.

DETAILED DESCRIPTION

Example embodiments are described in greater detail below with referenceto the accompanying drawings.

In the following description, like drawing reference numerals are usedfor like elements, even in different drawings. The matters defined inthe description, such as detailed construction and elements, areprovided to assist in a comprehensive understanding of the exampleembodiments. However, it is apparent that the example embodiments can bepracticed without those specifically defined matters. Also, well-knownfunctions or constructions are not described in detail since they wouldobscure the description with unnecessary detail.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items. Expressions such as “atleast one of,” when preceding a list of elements, modify the entire listof elements and do not modify the individual elements of the list. Forexample, the expression, “at least one of a, b, and c,” should beunderstood as including only a, only b, only c, both a and b, both a andc, both b and c, all of a, b, and c, or any variations of theaforementioned examples.

Hereinafter, a light detection and ranging (LiDAR) apparatus usinginterrupted continuous wave light will be described in detail withreference to the accompanying drawings. In the following drawings, likereference numerals refer to like elements throughout. Also, the size ofeach layer illustrated in the drawings may be exaggerated forconvenience of explanation and clarity. Furthermore, the exampleembodiments are merely described below, by referring to the figures, toexplain aspects of the present description, and the present exampleembodiments may have different forms. In the layer structure describedbelow, when a constituent element is disposed “above” or “on” to anotherconstituent element, the constituent element may include not only anelement directly contacting on the upper/lower/left/right sides of theother constituent element, but also an element disposedabove/under/left/right the other constituent element in a non-contactmanner.

FIG. 1 is a block diagram illustrating a schematic configuration of aLiDAR apparatus 100 according to an example embodiment. Referring toFIG. 1, the LiDAR apparatus 100 according the example embodiment mayinclude a continuous wave light source 110 that generates continuouswave light, a frequency modulator 120 that drives the continuous wavelight source 110 such that the continuous wave light source 110generates frequency modulated light, a beam steering device 130 thatemits or steers, toward an external object (e.g., a vehicle), frequencymodulated continuous wave light emitted from the continuous wave lightsource 110, a receiver 140 that receives light reflected from theexternal object and forms a reception signal, and a signal processor 150configured to extract distance information and speed information aboutthe external object based on the reception signal formed by the receiver140.

The continuous wave light source 110 is configured to continuouslyoscillate and emit continuous wave light having a waveform such as asine wave. In addition, the continuous wave light source 110 may beconfigured to emit laser light of an infrared band invisible to thehuman eye. For example, the continuous wave light source 110 may beconfigured to emit laser light having a wavelength in the range of about800 nm to about 2,000 nm.

The frequency modulator 120 controls the driving of the continuous wavelight source 110. The continuous wave light source 110 may be controlledby the frequency modulator 120 to generate frequency modulatedcontinuous wave light. For example, the modulation frequency of thefrequency modulator 120 may be about 10 kHz to about 10 MHz, and themodulation bandwidth thereof may be about 100 MHz to about 10 GHz.

In addition, the LiDAR apparatus 100 may further include an opticalamplifier 125 and an optical amplifier controller 126. The opticalamplifier 125 is configured to amplify the continuous wave lightgenerated by the continuous wave light source 110 and provide anamplified continuous wave light to the beam steering device 130. Theoptical amplifier controller 126 is configured to control the operationof the optical amplifier 125 to amplify continuous wave light based on acommand of the signal processor 150. For example, the optical amplifiercontroller 126 may control ON/OFF, amplification gain, and the like ofthe optical amplifier 125. The optical amplifier 125 may be, forexample, a high power amplifier having a gain of about 5 dB to about 30dB and having saturation output power of about 10 mW to about 1,000 mW.By using the optical amplifier 125 that is a high power amplifier, it ispossible to use a relatively low cost low power continuous wave laser asthe continuous wave light source 110.

The beam steering device 130 may include an optical phase array (OPA)device configured to one- or two-dimensionally scan the continuous wavelight generated by the continuous wave light source 110. The beamsteering device 130 may transmit the continuous wave laser lightamplified by the optical amplifier 125 in a one-dimensional (1D) ortwo-dimensional (2D) scanning manner toward a front local area. To thisend, the beam steering device 130 may steer laser light focused in anarrow area to a front one-dimensional or two-dimensional areassequentially or non-sequentially at a constant time interval. Forexample, the beam steering device 130 may be configured to emit laserlight from left to right or from right to left for front one-dimensionalareas, or be configured to emit laser light from left to right or fromright to left and from bottom to top or from top to bottom for fronttwo-dimensional areas.

For example, FIGS. 2A to 2C illustrate examples of a configuration andoperation of the beam steering device 130 for scanning laser light.Referring to FIG. 2A, the beam steering device 130 may include atransmission element array 133 including a plurality of transmissionelements 134 arranged two-dimensionally along a plurality of rows and aplurality of columns. The beam steering device 130 may further include adriving circuit for driving each of the transmission elements 134 of thetransmission element array 133. Each transmission element 134 may be,for example, a reflective antenna resonator that delays the phase ofincident light to reflect the incident light or a transmissive antennaresonator that delays the phase of incident light to transmit theincident light. The phase of reflected or transmitted laser light may bedetermined by a voltage applied to each transmission element 134 underthe control of the driving circuit.

In this structure, the direction of laser light emitted from thetransmission element array 133 may be controlled according to a phasedifference between pieces of laser light emitted from the plurality oftransmission elements 134. Specifically, the traveling direction of thelaser light may be controlled in a horizontal direction according to aphase difference Δϕ1 between pieces of laser light emitted from aplurality of transmission elements 134 arranged along the same row. Inaddition, the traveling direction of the laser light may be controlledin a vertical direction according to a phase difference Δϕ2 betweenpieces of laser light emitted from a plurality of transmission elements134 arranged along the same column.

For example, as shown in FIG. 2A, when the phase of the laser light isgradually delayed from a transmission element 134 disposed at the rightend to a transmission element 134 disposed at the left end in the samerow, the laser light travels in a left direction. An angle at which thelaser light travels in an azimuthal direction may be determined by aphase difference Δϕ1 between pieces of laser light emitted from twoadjacent transmission elements 134 in the same row. When the phasedifference Δϕ1 increases, the laser light is inclined further to theleft side, and when the phase difference Δϕ1 decreases, the laser lighttravels closer to the front side.

Furthermore, when the phase of the laser light is gradually delayed froma transmission element 134 disposed at the top to a transmission element134 disposed at the bottom in the same column, the laser light travelsdownward. In this case, an angle at which the laser light travels in anelevation angle direction may be determined by a phase difference Δϕ2between pieces of laser light emitted from two adjacent transmissionelements 134 in the same column. When the phase difference Δϕ2increases, the laser light is inclined further downward, and when thephase difference Δϕ1 decreases, the laser light travels closer to thefront side.

Referring to FIG. 2B, the laser light emitted from the transmissionelement array 133 is completely directed to the front side when thephase difference Δϕ1 is 0 and the phase difference Δϕ2 is 0. Also,referring to FIG. 2C, when the phase of the laser light is graduallydelayed from a transmission element 134 disposed at the left end to atransmission element 134 disposed at the right end in the same row, thelaser light travels in a right direction. When the phase of the laserlight is gradually delayed from a transmission element 134 disposed atthe bottom to a transmission element 134 disposed at the top in the samecolumn, the laser light travels upward.

Therefore, when the phases of pieces of laser light emitted from theplurality of transmission elements 134 of the transmission element array133 are individually controlled, the laser light may be steered in adesired direction. The transmission element array 133 may be configuredto apply voltages to the plurality of transmission elements 134independently from each other under the control of the driving circuit.The phase of laser light emitted from each transmission element 134 maybe determined by a voltage applied to the transmission element 134, andthe direction of laser light emitted from the transmission element array133 may be determined by a combination of voltages applied to theplurality of transmission elements 134.

In FIG. 2A to FIG. 2C, the transmission element array 133 is illustratedas including a plurality of transmission elements 134 arrangedtwo-dimensionally along a plurality of rows and a plurality of columns,but is not necessarily limited thereto. For example, the transmissionelement array 133 may include a plurality of transmission elements 134arranged one-dimensionally along one row and a plurality of columns oralong a plurality of rows and one column. In this case, the transmissionmodule 120 may transmit laser light in a one-dimensional (1D) scanningmanner toward the front.

So far, the beam steering device 130 has been described as scanninglaser light by using an optical phase array method, but is notnecessarily limited thereto. The beam steering device 130 may scan laserlight by another scanning method instead of the optical phase arraymethod. For example, the beam steering device 130 may include anactuator that rotates the continuous wave light source 110. In thiscase, the direction of the laser light may be adjusted by directlyrotating the continuous wave light source 110. In another example, thebeam steering device 130 may include a mirror that reflects laser lightand an actuator that rotates the mirror, or may include a micro electromechanical system (MEMS) device that controls the direction ofreflection of the laser light by electrically controlling a fine tilt ofthe mirror.

Light transmitted from the beam steering device 130 is reflected by anexternal object and returned to the LiDAR apparatus 100. The LiDARapparatus 100 may receive the light reflected from an external object,generate an electrical reception signal from the light, and obtaininformation about the external object from the electrical receptionsignal. When receiving light the reflected from the external object toform the electrical reception signal, frequency-modulated continuouswave light emitted from the continuous wave light source 110 may besplit and a portion of the frequency-modulated continuous wave light maybe used as local oscillator light for frequency analysis. To this end,the LiDAR apparatus 100 may further include a beam splitter 115 thatsplits the frequency-modulated continuous wave light emitted from thecontinuous wave light source 110 and provides most of thefrequency-modulated continuous wave light to the beam steering device130 and provides the remaining portion to the receiver 140. For example,the beam splitter 115 may be configured to provide at least 90% ofincident light to the beam steering device 130 and to provide theremaining portion to the receiver 140 as local oscillator light. Inparticular, the beam splitter 115 may be disposed in an optical pathbetween the continuous wave light source 110 and the optical amplifier125 to provide the optical amplifier 125 with most of the incident lightincident from the continuous wave light source 110.

The receiver 140 is configured to form an electrical reception signalfor interference light obtained by interference between light reflectedfrom an external object and local oscillator light provided from thebeam splitter 115. For example, the receiver 140 may include alight-receiving element 141 that receives light reflected from anexternal object, a beam combiner 142 that combines light received by thelight-receiving element 141 with local oscillator light provided fromthe beam splitter 115 to make the received light and the localoscillator light interfere with each other, and a photodetector 143 thatconverts the intensity of interference light into an electrical signal.The light-receiving element 141 may include, for example, a lens or alens array. The receiver 140 may further include a band pass filter orlow pass filter for removing noise components and obtaining interferencelight components. The receiver 140 may convert the interference lightinto an electrical signal through the photodetector 143 to form anelectrical reception signal. Since the interference light is in arelatively narrow frequency band, a relatively narrow band receiver maybe used as the receiver 140 compared to a receiver used in a pulsedLiDAR apparatus.

The signal processor 150 may extract distance information and speedinformation about an external object based on a reception signalreceived from the receiver 140. In addition, the signal processor 150may be configured to control the frequency modulator 120 to adjust afrequency modulation scheme, and to control the beam steering device 130to control a scanning operation. Although shown in FIG. 1 as separateblocks for convenience, the signal processor 150, the frequencymodulator 120, and the receiver 140 may be integrally implemented in onesemiconductor chip. Instead, the signal processor 150, the frequencymodulator 120, and the receiver 140 may be formed on one printed circuitboard. Alternatively, the frequency modulator 120 and the receiver 140may be integrally implemented as one semiconductor chip, and the signalprocessor 150 may be implemented as software that may be executed in acomputer and stored in a recording medium. According to another example,the signal processor 150 may be implemented as a programmable logiccontroller (PLC), a field-programmable gate array (FPGA), or the like.

According to the present example embodiment, the optical amplifier 125and the beam steering device 130 may be configured to interruptedly(intermittently or discontinuously) amplify frequency-modulatedcontinuous wave light under the control of the signal processor 150 andinterruptedly (intermittently or discontinuously) emit the amplifiedfrequency-modulated continuous wave light. For example, FIG. 3 is atiming diagram showing an operation of the LiDAR apparatus 100 shown inFIG. 1, according to an example embodiment. Referring to FIG. 3, thebeam steering device 130 may be configured to emit frequency-modulatedcontinuous wave light to the outside only during a first time T1 and notto emit the frequency-modulated continuous wave light to the outsideduring the second time T2, under the control of the signal processor150.

To this end, the signal processor 150 may activate the optical amplifier125 and the beam steering device 130 during the first time T1 and stopthe operations of the optical amplifier 125 and the beam steering device130 during the second time T2. Then, the light outputs of the opticalamplifier 125 and the beam steering device 130 are stopped during thesecond time T2, and thus, light is not emitted to the outside of theLiDAR apparatus 100. Even when the operation of the beam steering device130 is interrupted, the continuous wave light source 110 and thefrequency modulator 120 continue to generate frequency-modulatedcontinuous wave light without stopping operation to continuously providelocal oscillator light for forming a reception signal to the receiver140.

The signal processor 150 may control the beam steering device 130 toperiodically repeat the first time T1 for emitting continuous wave lightand the second time T2 for not emitting the continuous wave light. Inthis manner, the LiDAR apparatus 100 may emit pieces of transmissionlight Tx1, Tx2, Tx3, . . . in sequence. Each of the pieces oftransmission light Tx1, Tx2, Tx3, . . . is similar to pulsed light inthat it lasts only for the first time T1 and is interrupted and therebyis not transmitted for the second time T2. However, each of the piecesof transmission light Tx1, Tx2, Tx3, . . . is different from generalpulsed light in that it is frequency-modulated continuous wave light,the frequency of which changes over time. The frequency of the generalpulsed light remains constant over time when dispersion is not takeninto account.

The first time T1 for which each of the pieces of transmission lightTx1, Tx2, Tx3, . . . lasts and the second time T2 for which each of thepieces of transmission light Tx1, Tx2, Tx3, . . . is interrupted may beappropriately selected as necessary. For example, the first time T1 andthe second time T2 may be determined based on a time for which lightemitted from the LiDAR apparatus 100 is reflected from an externalobject and returned to the LiDAR apparatus 100, and the horizontalviewing angle, vertical viewing angle, horizontal scanning resolution,vertical scanning resolution, frame rate, and the like of the beamsteering device 130. The first time T1 may be selected within a range ofabout 1 ns to about 1,000 ns. In addition, when considering a time forreceiving pieces of reception light Rx1, Rx2, Rx3, . . . that arereflected from an external object and returned to the LiDAR apparatus100, the second time T2 may be determined to be longer than the firsttime T1.

The receiver 140 receives each of the pieces of reception light Rx1,Rx2, Rx3, . . . that are reflected from an external object and returned,and generates an electrical reception signal. As described above, theelectrical reception signal may be obtained from interference lightoccurring by interference between local oscillator light for frequencyanalysis provided from the continuous wave light source 110 and each ofthe pieces of reception light Rx1, Rx2, Rx3, . . . . For example, whenthe receiver 140 receives first reception light Rx1 at time t1 afterfirst transmission light Tx1 emitted at time t0 is reflected from anexternal object, an electric reception signal may be obtained byinterference between local oscillator light having a frequency componentof continuous wave light emitted from the continuous wave light source110 at the time t1 and the first reception light Rx1. In addition, whensecond transmission light Tx2 is emitted at time t2 and second receptionlight Rx2 is received at time t3, an electrical reception signal may beobtained by interference between local oscillator light having afrequency component of continuous wave light emitted from the continuouswave light source 110 at the time t3 and the second reception light Rx2.Similarly, when third transmission light Tx3 is emitted at time t4 andthird reception light Rx3 is received at time t5, an electricalreception signal may be obtained by interference between localoscillator light having a frequency component of continuous wave lightemitted from the continuous wave light source 110 at the time t5 and thethird reception light Rx3.

The first reception light Rx1, the second reception light Rx2, and thethird reception light Rx3 have frequency components that are modifiedaccording to the relative speed of an object. For example, when arelative speed with respect to an object is 0, the first reception lightRx1 may have the same frequency component as continuous wave lightemitted from the continuous wave light source 110 at the time t0. Inaddition, when an object approaches, the first reception light Rx1 mayhave a frequency component higher than that of the continuous wave lightemitted from the continuous wave light source 110 at the time t0. On thecontrary, when the object moves away, the first reception light Rx1 mayhave a frequency component lower than that of the continuous wave lightemitted from the continuous wave light source 110 at the time t0.

The signal processor 150 may extract distance information and speedinformation about an external object based on an electrical receptionsignal provided from the receiver 140. For example, the signal processor150 may be configured to analyze the frequency of a reception signal ina frequency-modulated continuous wave (FMCW) manner to extract distanceinformation and speed information about an object. In particular, thesignal processor 150 may analyze the frequency of a reception signal ina linear FMCW manner. To this end, the signal processor 150 may controlthe frequency modulator 120 to perform frequency modulation in such amanner that the frequency of continuous wave light emitted from thecontinuous wave light source 110 linearly increases with the period of athird time T3. For example, the frequency of the continuous wave lightemitted from the continuous wave light source 110 may linearly increasefrom a minimum frequency to a maximum frequency during the third timeT3, and then may linearly increase again from the minimum frequency tothe maximum frequency for the third time T3 thereafter.

FIG. 4 is a graph showing a frequency component of transmission lightand a frequency component of reception light in a linear FMCW method. InFIG. 4, the vertical axis of the graph represents frequency and thehorizontal axis of the graph represents time. Between the transmissionlight and the reception light, there is a time delay of Δt in ahorizontal direction and a frequency difference of fb in a verticaldirection. According to the linear FMCW method, distance information andspeed information may be extracted by performing a two-dimensional fastFourier transform (FFT) on an M×N matrix obtained by sampling M times ina frequency domain and N times in a time domain. Here, M and N arenatural numbers greater than one. For example, distance information maybe obtained by performing an FFT in a frequency domain, and speedinformation may be obtained by performing an FFT in a time domain.

In addition, the signal processor 150 may extract distance informationabout an object in a ToF manner, by using a time difference between atime at which transmission light is emitted and a time at whichreception light is received. There are already various ToF methods forobtaining distance information. In general, since it is difficult todirectly and accurately measure a time difference, distance informationabout an object may be extracted by using a phase difference betweentransmission light and reception light, the phase difference beingobtained by analyzing a waveform of a reception signal. In this case,through a cross-correlation between a reception signal and atransmission signal, only a signal component related to the transmissionsignal may be obtained from the reception signal, and the accuracy ofdistance measurement may be improved by analyzing the waveform of thesignal component related to the transmission signal.

Therefore, the signal processor 150 may obtain distance informationthrough an FMCW method and may obtain distance information through a ToFmethod. The signal processor 150 may adjust distance information aboutan object by using both the distance information obtained by the FMCWmethod and the distance information obtained by the ToF method in orderto further improve the accuracy of the distance measurement. Forexample, a distance obtained by the FMCW method and a distance obtainedby the ToF method may be simply averaged. Alternatively, a weightedaverage may be obtained by multiplying the distance obtained by the FMCWmethod by a first weight and multiplying the distance obtained by theToF method by a second weight, based on an error change according todistance in the FMCW method and an error change according to distance inthe ToF method. Alternatively, only the distance obtained by the FMCWmethod or the distance obtained by the ToF method may be selectedaccording to a distance range.

As described above, the LiDAR apparatus 100 according to the presentexample embodiment generates continuous wave light by using thecontinuous wave light source 110 that is a low power continuous wavelight source. In addition, the continuous wave light modulated by thefrequency modulator 120 is amplified by a high power optical amplifier131 and interruptedly emitted like a pulse. Therefore, the LiDARapparatus 100 according to the example embodiment may not need to use anexpensive high power continuous wave light source. In addition, sincethe high power optical amplifier 131 temporarily operates only for ashort time, the power consumption of the LiDAR apparatus 100 accordingto the present example embodiment is low. In addition, sincefrequency-modulated light is used, reflected light may be received usingthe receiver 140 of a relatively narrow band, thereby effectivelysuppressing noise.

In the example embodiment shown in FIG. 3, the beam steering device 130may be configured to emit frequency-modulated continuous wave light onlyone time for the third time T3. For example, during a first third timeT3, the beam steering device 130 may emit the first transmission lightTx1 and the receiver 140 may receive the first reception light Rx1.During a subsequent third time T3, the beam steering device 130 may emitthe second transmission light Tx2 and the receiver 140 may receive thesecond reception light Rx2. In this case, the third time T3 may be equalto the sum of the first time T1 and the second time T2.

However, the present disclosure is not necessarily limited thereto. Forexample, FIG. 5 is a timing diagram showing an operation of the LiDARapparatus 100 shown in FIG. 1, according to another example embodiment.Referring to FIG. 5, the beam steering device 130 may be configured toemit frequency-modulated continuous wave light twice during the thirdtime T3 under the control of the signal processor 150. For example, thebeam steering device 130 may emit first transmission light Tx1 andsecond transmission light Tx2 under the control of the signal processor150 during a first third time T3. Then, the receiver 140 may receivefirst reception light Rx1 and second reception light Rx2 during thefirst third time T3. During a subsequent third time T3, the beamsteering device 130 may emit third transmission light Tx3 and fourthtransmission light Tx4 and the receiver 140 may receive third receptionlight Rx3 and fourth reception light Rx4. In this case, the third timeT3 may be greater than the sum of the first time T1 and the second timeT2. In this manner, the beam steering device 130 may emitfrequency-modulated continuous wave light two or more times during thethird time T3.

Moreover, the beam steering device 130 may be configured to emittransmission light toward one area in front of the beam steering device130 under the control of the signal processor 150 and then emittransmission light toward another area in front of the beam steeringdevice 130. In other words, the beam steering device 130 maysequentially scan a plurality of local areas in front of the beamsteering device 130 in such a manner as to emit transmission light oneby one toward one area in front of the beam steering device 130. Forexample, the beam steering device 130 may emit the first transmissionlight Tx1 to a first area in front of the beam steering device 130 andthen emit the second transmission light Tx2 to a second area differentfrom the first area.

However, the present disclosure is not limited thereto, and in order toimprove a signal-to-noise ratio (SNR), the beam steering device 130 maybe configured to emit transmission light multiple times toward one areain front of the beam steering device 130 under the control of the signalprocessor 150 and then emit transmission light multiple times towardanother area. For example, the beam steering device 130 may sequentiallyemit first transmission light Tx1, second transmission light Tx2, andthird transmission light Tx3 toward a first area in front of the beamsteering device 130 and then sequentially emit fourth transmission lightTx4, fifth transmission light Tx5, and sixth transmission Tx6 toward asecond area different from the first area.

In this case, the signal processor 150 may accumulate electricalreception signals for the first reception light Rx1, the secondreception light Rx2, and the third reception light Rx3 sequentiallyreceived from the receiver 140 and may extract distance information andspeed information about an object in the first area based on theaccumulated electrical reception signals. Subsequently, the signalprocessor 150 may accumulate electrical reception signals for the fourthreception light Rx4, the fifth reception light Rx5, and the sixthreception light Rx6 sequentially received from the receiver 140 and mayextract distance information and speed information about the object inthe second area based on the accumulated reception signals.

Then, since the SNR of a reception signal is improved, the accuracy maybe improved compared to a case where the distance information and thespeed information are extracted with only one reception light obtainedfrom one area. The number of successive emissions of transmission lightfor one area may be differently selected according to a surroundingsituation. For example, when the SNR is good, the signal processor 150may determine to emit transmission light only once for one area. Inaddition, when the SNR is low, the signal processor 150 may determine tocontinuously transmit transmission light up to 1,000 times for one area.This method of accumulating a plurality of reception signals for onesame area and extracting distance information and speed information mayalso be applied to the example embodiment illustrated in FIG. 3.

In addition, the signal processor 150 may extract distance informationand speed information about the front object by analyzing the frequencyof a reception signal in a triangular FMCW method. For example, FIG. 6is a timing diagram showing an operation of the LiDAR apparatus 100shown in FIG. 1, according to another example embodiment. Referring toFIG. 6, the signal processor 150 may control the frequency modulator 120to perform frequency modulation in such a way that the frequency ofcontinuous wave light emitted from the continuous wave light source 110linearly increases for a third time T3 and linearly decreases for asubsequent fourth time T4. In this case, the frequency of the continuouswave light emitted from the continuous wave light source 110 maylinearly increase from a minimum frequency to a maximum frequency forthe third time T3 and then linearly decrease from the maximum frequencyto the minimum frequency for the subsequent fourth time T4. The signalprocessor 150 may control the frequency modulator 120 such that thethird time T3 for which the frequency of frequency-modulated continuouswave light linearly increases and the fourth time T4 for which thefrequency of the frequency-modulated continuous wave light linearlydecreases are periodically repeated.

In the example embodiment shown in FIG. 6, the beam steering device 130may be configured to emit frequency-modulated continuous wave light onlyone time for a third time T3 and emit frequency-modulated continuouswave light only one time for a fourth time T4. For example, during thethird time T3, the beam steering device 130 may emit first transmissionlight Tx1 and the receiver 140 may receive first reception light Rx1.During the fourth time T4, the beam steering device 130 may emit secondtransmission light Tx2 and the receiver 140 may receive second receptionlight Rx2. During a subsequent third time T3, the beam steering device130 may emit third transmission light Tx3 and the receiver 140 mayreceive third reception light Rx3, and during the fourth time T4, thebeam steering device 130 may emit fourth transmission light Tx4 and thereceiver 140 may receive fourth reception light Rx4. In this case, eachof the third time T3 and the fourth time T4 may be equal to the sum ofthe first time T1 and the second time T2. In addition, in the firsttransmission light Tx1 and the third transmission light Tx3 and thefirst reception light Rx1 and the third reception light Rx3, thefrequency linearly increases, and in the second transmission light Tx2and the fourth transmission light Tx4 and the second reception light Rx2and the fourth reception light Rx4, the frequency linearly decreases.

FIG. 7 is a graph showing a frequency component of transmission lightand a frequency component of reception light in a triangular FMCWmethod. In FIG. 7, the vertical axis of the graph represents frequencyand the horizontal axis of the graph represents time. As shown in FIG.7, graphs of the transmission light and the reception light showtriangular forms in which the frequency linearly increases with time andthen linearly decreases with time. There is a time delay of Δt betweenthe frequency peak of the transmission light and the frequency peak ofthe reception light. The peak position of the transmission light may beknown from local oscillator light for frequency analysis. The receptionlight has only some information of a frequency rising section and someinformation of a frequency falling section. For example, the firstreception light Rx1 and the third reception light Rx3 provide only someinformation of the frequency rising section, and the second receptionlight Rx2 and the fourth reception light Rx4 provide only someinformation of the frequency falling section. The signal processor 150may determine, as the frequency peak of the reception light, anintersection point obtained by extending the frequency rising slopes ofthe first reception light Rx1 and the third reception light Rx3 and thefrequency falling slopes of the second reception light Rx2 and thefourth reception light Rx4.

When a relative speed of an object in front is not 0, a frequency shiftoccurs in reception light received through the receiver 140, due to aDoppler effect. For this reason, there is a frequency difference by Fdbetween the frequency peak of the transmission light and the frequencypeak of the reception light. For example, when the front objectapproaches, the frequency of the reception light becomes higher than thefrequency of the transmission light, as shown in FIG. 7. On thecontrary, when the front object moves away, the frequency of thereception light becomes lower than the frequency of the transmissionlight.

In this case, a distance R and a relative speed V of the front objectmay be obtained by Equation 1 and Equation 2, respectively.

$\begin{matrix}{R = {\frac{{cT}_{m}}{2B}\frac{\left( {F_{bu} + F_{bd}} \right)}{2}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \\{v = {\frac{\lambda}{2}\frac{\left( {F_{bd} - F_{bu}} \right)}{2}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In Equations 1 and 2 above, B represents a frequency difference betweena minimum frequency and a maximum frequency of local oscillator light,Tm represents a time difference (i.e., a time span of the third time T3or the fourth time T4) between the minimum frequency and the maximumfrequency of the local oscillator light, F_(bu) represents a frequencydifference between the transmission light and the reception light in thefrequency rising section, F_(bd) represents a frequency differencebetween the transmission light and the reception light in the frequencyfalling section, λ represents the wavelength of the local oscillatorlight which corresponds to the minimum frequency in an initial stage(i.e., t=0), and c represents the speed of light. The signal processor150 may extract distance information and speed information about anobject in a triangular FMCW manner by using Equations 1 and 2 above,based on a reception signal obtained from transmission light emittedduring the third time T3 and reception light formed by reflecting thetransmission light, and a reception signal obtained from transmissionlight emitted during the fourth time T4 and reception light formed byreflecting the transmission light.

In addition, even in the example embodiment shown in FIG. 6, the signalprocessor 150 may obtain distance information by using an FMCW methodand may obtain distance information by using a ToF method. The signalprocessor 150 may improve the accuracy of distance information about anobject by using both the distance information obtained by the FMCWmethod and the distance information obtained by the ToF method.

In the example embodiment shown in FIG. 6, the beam steering device 130may be configured to emit transmission light toward one area in front ofthe beam steering device 130 for the third time T3 and the fourth timeT4 under the control of the signal processor 150 and then emittransmission light toward another area in front of the beam steeringdevice 130 for a subsequent third time T3 and a subsequent fourth timeT4. For example, the beam steering device 130 may emit the firsttransmission light Tx1 and the second transmission light Tx2 toward afirst area in front of the beam steering device 130 and then emit thethird transmission light Tx3 and the fourth transmission light Tx4toward a second area different from the first area.

However, the present disclosure is not limited thereto, and in order toimprove the SNR, the beam steering device 130 may emit transmissionlight multiple times, i.e., four or more times, toward one area in frontof the beam steering device 130 under the control of the signalprocessor 150 and then emit transmission light multiple times, i.e.,four or more times, toward another area. For example, the beam steeringdevice 130 may sequentially emit the first transmission light Tx1, thesecond transmission light Tx2, the third transmission light Tx3, and thefourth transmission light Tx4 toward the first area. In addition, thesignal processor 150 may accumulate electrical reception signals for thefirst reception light Rx1 and the third reception light Rx3 receivedfrom the receiver 140 in a frequency rising section and then accumulateelectrical reception signals for the second reception light Rx2 and thefourth reception light Rx4 received from the receiver 140 in a frequencyfalling section. The signal processor 150 may extract distanceinformation and speed information about an object in the first areabased on the reception signals accumulated in the frequency risingsection and the reception signals accumulated in the frequency fallingsection. The signal processor 150 may variably determine the number ofsuccessive emissions of transmission light for one area based on the SNRof reception signal.

In addition, in the example embodiment illustrated in FIG. 6, the beamsteering device 130 may be configured to emit frequency-modulatedcontinuous wave light only one time during each of the third and fourthtimes T3 and T4. For example, the beam steering device 130 emits thefirst transmission light Tx1 for a first third time T3 and emits thesecond transmission light Tx2 for the fourth time T4. In addition, thebeam steering device 130 emits the third transmission light Tx3 forasubsequent third time T3 and emits the fourth transmission light Tx4 forthe fourth time T4. In this case, each of the third time T3 and thefourth time T4 may be equal to the sum of the first time T1 and thesecond time T2.

However, the present disclosure is not necessarily limited thereto. Forexample, FIG. 8 is a timing diagram showing an operation of the LiDARapparatus 100 shown in FIG. 1, according to another example embodiment.Referring to FIG. 8, the beam steering device 130 may be configured toemit frequency-modulated continuous wave light twice during each of thethird and fourth times T3 and T4 under the control of the signalprocessor 150. For example, the beam steering device 130 may emit firsttransmission light Tx1 and second transmission light Tx2 under thecontrol of the signal processor 150 for a first third time T3 and mayemit third transmission light Tx3 and fourth transmission light Tx4 forthe fourth time T4. Then, the receiver 140 may receive first receptionlight Rx1 and second reception light Rx2 for the first third time T3 andmay receive third reception light Rx3 and fourth reception light Rx4 forthe fourth time T4. In addition, during a subsequent third time T3, thebeam steering device 130 may emit fifth transmission light Tx5 and sixthtransmission light Tx6 and the receiver 140 may receive fifth receptionlight Rx5 and sixth reception light Rx6. In this case, each of the thirdand fourth times T3 and T4 may be greater than the sum of the first timeT1 and the second time T2. In this manner, the beam steering device mayemit frequency-modulated continuous wave light two or more times duringeach of the third and fourth times T3 and T4.

FIG. 9 is a block diagram illustrating a schematic configuration of aLiDAR apparatus 200 according to another example embodiment. Referringto FIG. 9, the LiDAR apparatus 200 according to another exampleembodiment may include a continuous wave light source 110 that generatescontinuous wave light, a beam steering device 130 that emits thecontinuous wave light emitted from the continuous wave light source 110to the outside, a receiver 140 that receives light reflected from anexternal object to form a reception signal, and a signal processor 150configured to extract distance information and speed information aboutan object based on the reception signal formed by the receiver 140. Inaddition, the LiDAR apparatus 200 may further include a beam splitter115 that splits the continuous wave light emitted from the continuouswave light source 110 and provides most of the continuous wave light tothe beam steering device 130 and provides the remaining portion to thereceiver 140 as local oscillator light for frequency analysis. Inaddition, the LiDAR apparatus 200 may further include an opticalamplifier 125 disposed in an optical path between the beam splitter 115and the beam steering device 130 to amplify the continuous wave light,and an optical amplifier controller 126 that drives the opticalamplifier 125.

The LiDAR apparatus 200 of FIG. 9 is different from the LiDAR apparatus100 shown in FIG. 1 in that the LiDAR apparatus 200 does not include thefrequency modulator 120. In this case, the continuous wave lightprovided from the continuous wave light source 110 to the beam steeringdevice 130 may not be frequency-modulated and maintains a constantfrequency. Accordingly, the operation of the LiDAR apparatus 200 shownin FIG. 9 is the same as that in which the frequency modulator 120 doesnot perform a frequency modulation operation in the LiDAR apparatus 100of FIG. 1. Also in the LiDAR apparatus 100 of FIG. 1, under the controlof the signal processor 150, the frequency modulator 120 may keep theoperating frequency of the continuous wave light source 110 constantwithout performing a frequency modulation operation. However, ifnecessary, the LiDAR apparatus 200 that does not include the frequencymodulator 120 may be manufactured in a manufacturing stage. For example,the LiDAR apparatus 200 of FIG. 9 may be provided at a lower cost thanthe LiDAR apparatus 100 of FIG. 1.

FIG. 10 is a timing diagram schematically showing an operation accordingto an example embodiment of the LiDAR apparatus 200 shown in FIG. 9.Referring to FIG. 10, the beam steering device 130 may be configured toemit continuous wave light to the outside only during a first time T1and not to emit the continuous wave light to the outside during a secondtime T2, under the control of the signal processor 150. In addition, thesignal processor 150 may control the beam steering device 130 toperiodically repeat the first time T1 for emitting the continuous wavelight and the second time T2 for not emitting the continuous wave light.In this manner, the LiDAR apparatus 200 may sequentially emit pieces oftransmission light Tx1, Tx2, Tx3, . . . . Each of the pieces of lightsTx1, Tx2, Tx3, . . . is similar to pulsed light in that it lasts onlyfor the first time T1 and is interrupted for the second time T2.However, each of the pieces of transmission light Tx1, Tx2, Tx3, . . .is different from general pulsed light in that it is continuous wavelight having only one frequency component. For example, general pulsedlight having a square or triangular waveform or the like may have afundamental frequency component and a plurality of harmonic frequencycomponents.

The receiver 140 receives each of pieces of reception light Rx1, Rx2,Rx3, . . . that are reflected from an external object and returned, andgenerates an electrical reception signal. As described above, theelectrical reception signal may be obtained from interference lightoccurring by interference between local oscillator light for frequencyanalysis and each of the pieces of reception lights Rx1, Rx2, Rx3, Thepieces of reception light Rx1, Rx2, Rx3, . . . have frequency componentsthat are modified by a Doppler effect according to the relative speed ofan object. The signal processor 150 may be configured to extractdistance information about an object by analyzing the waveform of areception signal by using a ToF method and extract speed informationabout the object by analyzing the frequency of the reception signal by aDoppler method.

Also in the example shown in FIG. 10, the beam steering device 130 maybe configured to emit transmission light toward one area in front of thebeam steering device 130 under the control of the signal processor 150and then emit transmission light toward another area in front of thebeam steering device 130. Instead, the beam steering device 130 may beconfigured to emit transmission light multiple times toward one area infront of the beam steering device 130 under the control of the signalprocessor 150 and then emit transmission light multiple times towardanother area. The signal processor 150 may accumulate a plurality ofelectrical reception signals obtained from pieces of reception lightreflected from the same area and may extract distance information andspeed information about an object in the area based on the accumulatedelectrical reception signals.

The LiDAR apparatuses 100 and 200 described above may be mounted on avehicle and configured to extract distances from vehicles in front ofthe vehicle and relative speed information. However, the LiDARapparatuses 100 and 200 are not necessarily applicable only to vehicles.For example, the LiDAR apparatuses 100 and 200 according to the presentexample embodiment may be mounted on a ship, an aircraft, a drone, orthe like in addition to a vehicle and used to search and avoid obstaclesin front of the ship, the aircraft, the drone, or the like.

While not restricted thereto, an example embodiment can be embodied ascomputer-readable code on a computer-readable recording medium. Thecomputer-readable recording medium is any data storage device that canstore data that can be thereafter read by a computer system. Examples ofthe computer-readable recording medium include read-only memory (ROM),random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, andoptical data storage devices. The computer-readable recording medium canalso be distributed over network-coupled computer systems so that thecomputer-readable code is stored and executed in a distributed fashion.Also, an example embodiment may be written as a computer programtransmitted over a computer-readable transmission medium, such as acarrier wave, and received and implemented in general-use orspecial-purpose digital computers that execute the programs. Moreover,it is understood that in example embodiments, one or more units of theabove-described apparatuses and devices can include circuitry, aprocessor, a microprocessor, etc., and may execute a computer programstored in a computer-readable medium.

The foregoing exemplary embodiments are merely exemplary and are not tobe construed as limiting. The present teaching can be readily applied toother types of apparatuses. Also, the description of the exemplaryembodiments is intended to be illustrative, and not to limit the scopeof the claims, and many alternatives, modifications, and variations willbe apparent to those skilled in the art.

What is claimed is:
 1. A light detection and ranging (LiDAR) apparatuscomprising: a continuous wave light source configured to generatecontinuous wave light; a beam steering device configured to emit thecontinuous wave light to an object for a first time and stop emittingthe continuous wave light to the object for a second time; a receiverconfigured to receive the continuous wave light that is reflected fromthe object to form a reception signal; and a signal processor configuredto obtain distance information and speed information about the objectbased on the reception signal.
 2. The LiDAR apparatus of claim 1,wherein the beam steering device is further configured to periodicallyrepeat emitting the continuous wave light for the first time andstopping emitting the continuous wave light for the second time.
 3. TheLiDAR apparatus of claim 1, wherein the second time is greater than thefirst time.
 4. The LiDAR apparatus of claim 1, wherein the first time isin a range of 1 ns to 1,000 ns.
 5. The LiDAR apparatus of claim 1,further comprising: a beam splitter configured to provide a firstportion of the continuous wave light generated by the continuous wavelight source to the beam steering device so that the first portion ofthe continuous wave light is emitted to and reflected from the object,and then received by the receiver, and provide a second portion of thecontinuous wave light to the receiver, wherein the receiver is furtherconfigured to form the reception signal by combining the first portionof the continuous wave light received by the receiver, and the secondportion of the continuous wave light provided from the beam splitter,and causing the first portion and the second portion of the continuouswave light to interfere with each other.
 6. The LiDAR apparatus of claim1, further comprising: an optical amplifier configured to amplify thecontinuous wave light generated by the continuous wave light source andprovide the amplified continuous wave light to the beam steering devicefor the first time, and stop amplifying and outputting the continuouswave light for the second time.
 7. The LiDAR apparatus of claim 1,wherein the beam steering device is further configured to emit thecontinuous wave light multiple times toward a first area in front of thebeam steering device and then emit the continuous wave light multipletimes toward a second area different from the first area.
 8. The LiDARapparatus of claim 7, wherein the signal processor is further configuredto: accumulate a plurality of first reception signals received from thefirst area and obtain distance information and speed information about afirst object in the first area based on the accumulated plurality offirst reception signals; and accumulate a plurality of second receptionsignals received from the second area and obtain distance informationand speed information about a second object in the second area based onthe accumulated plurality of second reception signals.
 9. The LiDARapparatus of claim 1, further comprising: a frequency modulatorconfigured to drive the continuous wave light source such that thecontinuous wave light source generates frequency-modulated continuouswave light, wherein the beam steering device is further configured toemit the frequency-modulated continuous wave light to the object for thefirst time and stop emitting the frequency-modulated continuous wavelight to the object for the second time.
 10. The LiDAR apparatus ofclaim 9, wherein the signal processor is further configured to obtainthe distance information and the speed information about the object byanalyzing a frequency of the reception signal in a frequency-modulatedcontinuous wave (FMCW) manner.
 11. The LiDAR apparatus of claim 10,wherein the frequency modulator is configured to linearly increase afrequency of the frequency-modulated continuous wave light for a thirdtime.
 12. The LiDAR apparatus of claim 11, wherein the third time isequal to a sum of the first time and the second time, and wherein thebeam steering device is further configured to emit thefrequency-modulated continuous wave light once for the third time. 13.The LiDAR apparatus of claim 11, wherein the third time is greater thana sum of the first time and the second time, and the beam steeringdevice is further configured to emit the frequency-modulated continuouswave light multiple times for the third time.
 14. The LiDAR apparatus ofclaim 10, wherein the frequency modulator is further configured tolinearly increase a frequency of the frequency-modulated continuous wavelight for a third time and linearly decrease the frequency for a fourthtime, and wherein the third time for increasing the frequency of thefrequency-modulated continuous wave light and the fourth time fordecreasing the frequency of the frequency-modulated continuous wavelight are periodically repeated.
 15. The LiDAR apparatus of claim 14,wherein each of the third time and the fourth time is equal to a sum ofthe first time and the second time, and wherein the beam steering deviceis further configured to emit the frequency-modulated continuous wavelight once for the third time and emit the frequency-modulatedcontinuous wave light once for the fourth time.
 16. The LiDAR apparatusof claim 14, wherein each of the third time and the fourth time isgreater than a sum of the first time and the second time, and whereinthe beam steering device is configured to emit the frequency-modulatedcontinuous wave light multiple times for the third time and emit thefrequency-modulated continuous wave light multiple times for the fourthtime.
 17. The LiDAR apparatus of claim 15, wherein the signal processoris further configured to obtain the distance information and the speedinformation about the object in an FMCW manner based on the receptionsignal obtained from reflected light of the frequency-modulatedcontinuous wave light emitted for the third time and the receptionsignal obtained from reflected light of the frequency-modulatedcontinuous wave light emitted for the fourth time.
 18. The LiDARapparatus of claim 10, wherein the signal processor is furtherconfigured to obtain the distance information about the object byanalyzing a waveform of the reception signal in a time of flight (ToF)manner.
 19. The LiDAR apparatus of claim 18, wherein the signalprocessor is further configured to adjust the distance information aboutthe object based on the distance information extracted in the ToF mannerand the distance information extracted in the FMCW manner.
 20. The LiDARapparatus of claim 1, wherein the signal processor is further configuredto extract the distance information about the object by analyzing awaveform of the reception signal in a TOF manner and obtain the speedinformation about the object by analyzing a frequency of the receptionsignal in a Doppler manner.
 21. A method of sensing an object by a lightdetection and ranging (LiDAR) apparatus, the method comprising:generating continuous wave light; splitting the continuous wave lightinto a first portion and a second portion; amplifying the first portionof the continuous wave light; intermittently emitting the amplifiedfirst portion of the continuous wave light toward an object, theamplified first portion of the continuous wave light being reflectedfrom the object and received by a receiver of the LiDAR apparatus;providing the second portion of the continuous wave light to thereceiver; generating a reception signal by combining the first portionof the continuous wave light and the second portion of the continuouswave light that are received by the receiver; and obtaining distanceinformation and speed information about the object based on thereception signal.